Fettelite with Proustite

Glasberg quarry

Nieder-Beerbach

Odenwald

Hessen

Germany

8.0 by 4.5 by 2.7 cm – Small cabinet specimen (under 10 cm)

Fettelite is complex silver mercury arsenic sulfide (sulfosalt). A local geologist named M. Fettel originally noticed the mineral at this, the type locality (Wang & Paniagua, 1996). Fettelite appears hexagonal, forming thin red plates, sometimes with a visible hexagonal outline. The individual plates probably do not exceed 0.5 mm across, but red foliated patches of fettelite in this calcite seam cover several square centimeters of the specimen. This is a rich specimen, with excellent micromount potential. Later study by Bindi et al. (2009) on Chilean material afforded a crystal structure solution and demonstrated monoclinic symmetry in the mineral. Further work on German material by Bindi et al. (2012) found significant Fe substitution for Hg, and implies the existence of a related isostructural mineral species. A rare silver mineral!